Many machines, such as cars, are equipped with a form of “kill switch.” The kill switch allows some or all of the functionality of the machine to be disabled. For example, a car may have a hidden switch (e.g., under the dashboard, in the glove compartment, etc.), that disables the car by shutting off the fuel supply, the ignition, or some other aspect of the car's operation. Kill switches may be used to disable a variety of machines. A car is an example of a machine that could have a kill switch, although other machines could also have such switches.
There are a small number of places where kill switches may be hidden, so most thieves know where to look for them. Moreover, the switch may be turned on or off, so once a thief finds the switch, he or she may turn the switch on and re-enable the car (or other type of machine that the kill switch is used for). Additionally, the fact that the switch is typically located on the machine to be disabled means that activating the kill switch involves being in physical proximity to the machine, so it is difficult for the owner to enable or disable the machine unless the owner is physically in the same place as the machine.